Method for color separation



Oct. 14, 1952 w. c. HUEBNER METHOD FOR COLOR SEPARATION 2 SHEETS SHEET 1 Filed July 18, 1947 IN VEN TOR.

lab [ham C. :Hwebner AGENT Oct. 14, 1952 w. c. HUEBNER METHOD FOR COLOR SEPARATION 2 SHEETS-SHEET 2 Filed July 18, 1947 INVENTOR. William 61 Jfiwner AGUWKT Patented Oct. 14, 1952 UNITED STATES PATENT OFFICE.

2,614,042 METHOD FOR COLOR SEPARATION William C. Huebner, New York, N. Y. Application July 18, 1947, Serial No. 761,783 6 Claims. (01. 95-2) The present invention relates to improvements in photographic reproduction of color copy and, in particular, to methods of and means employed for making component color separation records on photo sensitive plates or film from color copy with the aid of monochromatic illumination.

There are two general classifications of color copy which may be reproduced in the graphic arts. The first includes opaque color copy such, for instance, as a painting or drawing made with color media as water colors, oil paints, pastels, or dyes on opaque surfaces. Copyof this description can only be viewed or photographed with reflected light from the surface thereof. The second class of color copy includes transparencies, usually produced with color sensitive film. Film or plates of this description are in general use employing color dyes to represent the images on transparent surfaces and these must be illuminated from the back of the plate or film and viewed or photographed from the front.

With the increasing demand for printed color reproduction it becomes necessary to reproduce step in color processing.

Color begins with light. Hence, color copy must be illuminated evenly with the proper intensity and also the proper quality of light. Experience with white flame carbon arc lamps to illuminate copy for photographic color reproduction has indicated certain limitations in this light source. The light from a carbon arc is emitted from a small space between the carbons, requiring that the arcs be spread and moved away from the. copy to avoid hot spots" resulting from non-uniform illumination, quite frequently, with the use of carbon arc lamps, there is a limit to the possible movement of the arc lamps away from the copy, particularly in crowded photographic galleries where space is not available,

and more frequently a uniform illumination is difiicult because the ditsance from the copy from the camera lens does not permit the most desirable placement of the arc lamps.

A further difficulty with carbon arc lamps occurs because the space between the carbons, when the lamp is on, varies with fluctuations in the line voltage supplying the lamps and also with non-uniform combustion of the carbons. Thus, the length and position of the are core is constantly moving and changing in size, affecting the intensity of light and its color characteristics applied to the color copy, and consequently aifecting the photographic plate or film being produced.

Corrective control devices such as voltage regulators for the current supply line and electronic photo tube or photo cell light quantity and time integrators are helpful, but they do not correct uneven illumination which is always present when arc lamps are used to illuminate fiat copy surfaces. Intense heat from are lamps and carbon dust resulting from combustion are also undesirable and inconvenience results from are lamp illumination.

When producing color separation negatives for printing processes the light projected to or projected through the copy must be filtered according to the technique employed. Color filters usually consist of a transparent film base dye stained with a color which is intended to be complementary to that color to be separated and printed in colored ink. For example, in three color process work, a purple color filter is used in producing the yellow plate, an orange filter for the blue plate and a green filter for the red plate. Frequently all three filters are exposed for a short period of time to produce a black plate. Color filters are usually inserted in a slot in the barrel of the camera lens and centered between the nodal points in the lens or, they may be placed directly in the path of the image.

The separated color is represented in the negative by transparent graduations of tone value comprising the color image. In the case of relief printing plates, when this negative image is printed by contact upon a sensitized printing plate, the action of the printing light takes place through the transparent portion of the negative rendering the image relatively insoluble and,

when developed, the light hardened image becomes a positive image. The image resists etching acid, and a relief etched plate is obtained, and

ink applied to the relief image yields on the paper the selected color image which was filtered or separated as above described.

The time consuming procedure now follows since the values of each component color separation must be corrected for deficiencies by staging, etching, and re-etching locally where the separation is faulty and out of balance and where it does not faithfully render the true values of the color copy. There are various causes for faulty separation color values as, for instance, impure colors in the filter; also the separations may be out of balance with each other. Furthermore, the separations may not be the true complementaries of the color inks used in printing.

Copy color also has its effect, the white base of opaque color copy being only approximately white for photographic action. Likewise, all full strength colors, including black, reflect some light and affect the sensitized plate or film being exposed in the camera accordingly. Thus, two pieces of copy will afiect the sensitized surface differently for the same exposure, and retouching and re-etching are needed to attain a balance when printed with one set of color inks.

It is well known by expert color printers that the hues and chroma of yellow and blue printing inks combined to produce green yield only approximately and to a limited extent the varieties of greens that are visible in a fine color transparency. Similarly, purples and lavenders are limited in their brilliance because of the limitations of the red and blue inks which produce purple. These defects, persist regardless of expert re-etching or re-touching and the many hours of costly labor consumed in the production of photo mechanical photo printing plates.

Labor, in addition to that of camera operators, which is required to balance the color result is variable. The. judgement of color etchers, retouchers, and provers varies constantly and further affects the quality of the result through expert guesswork, thus increasing the time required toproduce a color job and increasing the delays andunnecessary expense. in the final production.

It is the principal aim of the. present invention to improve upon thesedefective and time consuming procedures by providing simpler and more. dependable equipment embodying improved operational methods.

In my invention I provide, in'part, an improved .means for reflecting color light to the camera from. opaque copy and for transmitting color light to the. camera through transparent copy for producing color separations which includes the substitution .of white light flash tubes for arc lamps; as asource of light and, in place of filters, I break down the source of light into its component color bands and use the specific color desired. A'fl'ash tube isplaced behind a prism at apoint where the spectrum colors are brightest and where the color bands emitted are at their maximum width. All colors of the spectrum appear through theprism as narrow bands varying in width, and provision is made for adjustable rotation of the prism on its axis and for adjustmentjat right angles thereto. A masking device having anelongated adjustable slot is provided between the prism and copy to permit only the selected color band to be projected therethrough. Suitable adjustments for the mask permit the projected color light to illuminate the color copy in a manner whereby the. entire band is within full range of the lens of a camera for the full area of the copy when the light band is moved over the copy. The slot opening is. set adjacent the copy whereby the color light will illuminate at its most brilliant focus from the full length of the slotted mask.

The flash lamp and prism, including the adjustable light masks are mounted as a unit and are moved at a given speed with respect to the copy so that the projected light will traverse the entire surface of the copy. The flash tube is connected with a rotating switch which sends pulses of current built up in the condensers to the tube at timed intervals during movement of the device across the face of opaque copy or across the back of transparent copy.

All other light is excluded from the space between the copy and the lens in order to permit the lens to project the entire image area during flash illumination on the color sensitive plate or film in the camera. Thus, only the pure color of the spectrum is used in my illuminator to filter out the color of the copy needed to re-produce the selected color for printing with ink or die from a set of photo mechanical color plates.

Adjustments are provided to position the flash tube, the prism, and the open slots to obtain a balance of complementary colors using prescribed arangement for two, three, four, five and six color combinations, according to requirements for predetermined color results needed for the ink or die multi-color printed edition produced on printing presses. For example, the use of following approximate color bands constitute the procedure for a five color set of separation plates or films:

The purple light band is ink plate.

The green light band is used for the red ink plate.

The orange light band is used for the blue ink plate.

The red light band isused for the green ink plate.

The yellow light'band is used ink plate.

Combination exposures of two or more color bands may be used to produce a black or'neutral separation plate or film, and also for split colors such as half strength red or blue.

As alternative construction, elements of the preferred embodiment of my invention described above, including the flash tube apparatus, may be used and the use of prisms avoided by substituting suitable glass or film filters covering the flash tube slot; furthermore, selected color may be substituted for white light, flash tubes, and filters. In either case will give improved'performance'compa-red to the use of arc lamps.

Other objects and features of novelty will be apparent from the following description of a preferred physical embodiment of the invention taken in connection with the drawings, in which Y Figurel is a front elevation view of the mechanism of my invention,

Figure 2 is an enlarged fragmentary view'of the centrally located mechanisms of Figure 1, with an enclosing cover removed to show constructional details,

Figure 3 is a view taken on line ure 2,

Figure 4 is a fragmentary side elevation view of counterbalancing devices taken on line 4-4 of 'Figure l, and

Figure 5 is a side elevation similar to the left hand portion of Figure 3, showing alternative lamp construction according to my invention.

Referring to the drawings, the embodiment of the invention illustrated therein is adapted to be used with a precision color camera of the overhead type. wherein the relatively large and heavy mechanical components are suspended from an elevated supporting structure. Persons used for the yellow for the purple 33 Of Figfamiliar with photographic reproduction for printing and engraving will be familianwith the basic elements of copying cameras includingthe camera itself and the copyboard used for supportingtand positioning copy with respect to the lens of the camera to give prescribed enlargement or reduction of size. Persons skilled in the art will also be familiar with the conventional sources of illumination for cameras of this kind which are likewise adjustably sup ported either individually from the floor or on carriages which are moveable on the camera framework. While reference is made herein to the camera and the copyboard, details of construction of these elements are omitted for the sake of clarity, the invention being mainly directed to the illumination of the, copy. In.Figure 1, an illuminator supporting framework, generally indicated at, 19, is shown suspended from the overhead bars H, these .bars being disposed longitudinally of the camera and used primarily tosupport the camera and copyboard. Framework I is constructed so that it may be rolled along bars H for positioning with respect. to the copy and the lens of the camera,travelling on companion three-way roller guides, l2located on the right and left sides thereof, which ride on tracks [55 secured to bars H. .Provision is made so thatthe central portion of :the framework, including the vertical frame members I1, may also .be moved from side to, side on opposed pairs of horizontally moveabletrolleys 14 which are arranged to roll on cross-member I suspended between depending brackets on guides 12. tween the frame members I! at their low extremity, thus maintaining parallelism. Copy l8, shown here in phantom, is suitably arranged on the copyboard, centrally of the two vertical frame members I'I, so that it is in position for photographing.

- The framework It! forms the support for illuminator devices comprising mainly a top illuminator 2lland a bottom illuminator 2!, which will be hereinafter described in detail, located either in front of copy it between the copyboard and the camera for producing light to be reflected from opaque copy, or arranged behind transparent copy for transmitting light therethrough to the camera. This description treats the arrangement for reflected light from copy and it will be obvious that transposition and re-arrangement of parts may be made to adapt the equipment for transmission of light through transparencies.

Illuminator assemblies 29 and 2i cooperate to focus their emitted light to a narrow band 190i copy l8, and theyare adjustably fastened together, one above the other, by the side braces 23 which are suitably fixed thereto and which may be moved and clamped with respect to one another to vary the spacing between the illuminators. As an assembly, illuminators and 2| move vertically onthe framework [0 and in so moving cast light over the entire copy area, control for movement being provided principally by two pairs of trolleys 25 which straddle and roll on the depending bars l1. Trolley 25 are secured indirectly with the top illuminator 20, being fixed to cross member 26 which is rigidly fastened to this, illuminator.

Driving means is provided to move the illuminator assembly as indicated, whereby the assembly is raised or lowered as a unit, the drive originating in a small reversibleelectric motor 24 Tie bar l6 extends besuitably mounted on. he top illuminator 20. Worm 21 on the shaft of motor 24 engages and drives a worm wheel 28 on horizontal shaft 29 thereabove which is trunnioned in bosses 30 on cross bar 26. As shaft 29 is turned spur gears 31 which engage racks 32 on the vertical frame members ll, being fastened thereto, will also turn and will move the illuminators upward or downward depending upon the direction of motor rotation. Suitable electrical. switching and controllingdevices, not shown, are provided in circuit with motor 26 to initiate and regulate the drive for the illuminator assembly either upwardly or downwardly over the face of the copy.

A counterbalance is provided for the illuminators to equalize the upward and downward drivingforce requirements. This device, as shown in Figure 4, consists of a pair of supporting cables 35, fastened to the eye bolts 36 fixed to the ends of cross-member26, thence trained over pulleys 31 suitably fastened above trolleys l4, and finally extending down over the opposite side of the framework to engage a pair of counterbalancing weights 38. Springs may bev substituted in place of weights38 if desired, the important feature being the balancing provision whereby a small motor may be made to serve the driving requirement in either direction.v

It will be understood at this point that the illuminator assembly moves continuously and at a relatively slow speed when motor 24 is operating. Timed to this movement, a commutator 40, fastened to the right hand end of shaft 29, with suitable switching accessories 39 and current supply provides electrical impulses to trip the illumination means, as will be more clearly pointed out as the specification proceeds; Referring now to Figures 2 and 3, the illuminators 2D and 2! are substantially identical, each being providedwith a callibrated tubular flash lamp 4!, operated through high capacity.electrical circuits, not illustrated, to emit ;a desired intensity of illumination at a desired spectral composition. Lamps 41 are sufficiently long .so that they extend over the entire width of the maximum size of copy to be photographed and they are retained in holding sockets 42, mounted against the inner surface of the end enclosing covers 43, with electrical connecting leads 44 directed thereto from commutator 40 and its switching means previously mentioned.

By reason of their operating characteristics, photographic lamps of this style are intermittently flashed in order that a sufficient period of time will be permitted between flashes for the lamps to cool, during which interval of time a charge is built up in the condensers in the lamp circuits. As arranged, the flash of both lamps is simultaneous, both lamp circuits being connected with the single commutator 40; however, by using a dual commutator or with the use of other de-' vices the flash lamp may be operated alternately if there is an advantage in such operation.

Partially surrounding lamps 4! between the end enclosing covers 43 are the semi-cylindrical lamp housing covers 45 which are hinged with the main illuminator housings 46 so that they may swing away for lamp repairs or replacement. The main illuminator housings 46 are likewise located between the end enclosing covers 43, forming light tight enclosures, each of which contains a triangular optical glass prism 41 substantially coextensive in length with the flash tubes and receiving light therefrom through an elongated slotted aperture 48 inthe main illuminator housing. The quantity of light passing'from aperture.

48 to: prism 41 maybe regulated by the adjustablyguided masksn lg fixed adjacent the aperture and. moveable toward and away from each other by means of, the threadedadjusting screws 50 located at the sides of the:illuminators and projecting through housings 46iwhich, ontheir threaded ends, engage right; and leftv :hand threaded lugs 5i, 5! on the masks.

Each prism, 41, Figure 2,-is retainedbetween a pair of fiat cylindrical mounting. discs suitably calibrated for angular positionin having shaft extensions 55a integral therewith which project through both, end covers 43. Hand wheels 56 at.- tachedto shaft extensions 55a permitgthe prism to be angularlyadjusted onits axisbymanipulation at the outside of the illuminator housing. Journalling of the shaft extensions and rectilinear adjustment of the prism: with respectgto its axis is provided by associating the mounting discs 55 with transversely moveable slides 57, which, in turn, are guided on vertically moveable slides 58. Intermediate of the mounting. discs 55. and. the transverse slides 57 are large anti-frictionwashers 59 which are fitted over the shaft extensions 55a: to provide the proper spacing. between the mounting discs 55 and the transverse slides 51 and to allow angular. movement without objectionable frictional resistance.

The transverse slides 5I-"are substantially flat square platesdrilled for the passage therethrough and. journalling therein ofithe extension shafts 55a, beveled on one edge for confinement against a corresponding reversely'beveled projecting edge of the vertical slides 53. cm their edges opposite to'the beveled edges, transverseslides 57. are provided with rack teeth which mesh with spur gears 60 onthe horizontally disposed adjusting shaft 6 I which is trunnioned in the vertical slides 58 and which projects through the covers 43. Adjusting knobs 62 located on the El permit this shaft to turned,.spurgears 60 will move slides 5'1 transverselyof the illuminator assembly. By reason of the interconnection ofthe slides 51' with the extension shafts 55a of discs 55, the prism 47 will alsobe moved in a transverse direction.

A similar constructionvis used for the vertical slide members 58 which have rackteeth cut on one edge and are guided for vertical movement by gibs 63, Figure 3, :directly fastened to end plates 43. Adjusting shaft 84 is trunnioned directly in end covers 43 and carries a pair of spur gears 65 mounted thereon. This shaft may be turned by either of the knurled knobsBB to move the plates 58 which, in turn, will carry therewith the plates 5Tand likewise discs 55 to which theprismll is attached.

End-enclosing covers '23 are providedwith suitableclearance for the adjusting shafts and for the extension shaft on discs 55. Inasmuch as the latter will move both transversely and vertically with respect to the covers, it is necessary that this clearance takethe form of an enlarged circular opening. The: clearance in end covers 43 required for the transverse adjusting shaft 6| may be a vertical elongated slot since this element moves only vertically with respect thereto, being trunnioned inslides58. Clearance forrotation only is required in covers 43 for shaftfitsince it is trunnioned therein as heretofore explained. Transverse clearance is also'required in the vertically adjustable plate 58 to permit the-prism, discs 55,- and transverse plates 51 to move transe ends of adjusting shaft be turned, and when 8, versely without affecting the transversely fixed position of those plates.

Referring particularly to Figure 3, light passing through prism! 1 is directed obliquelyv therefrom, dependent upon the wave length, a portion of which is permittedtopass, through the elongated aperture-65 in'housing 46 and. thence between the,

adjustable masks 69, constructed similarly to the masks '49. Masks 69 may be adjusted for a prescribed width of aperture by turning either of the knurled-head screws ,10 which engage the right and left hand threaded lugs;H, H onmasks 69. From the .illuminatorhousing, the particular band of light passing through masks 69 is directed tobe intercepted by the. copy 18 at the narrow width band 19, which is infull range of the lens of the camera,sshown tothe left of Figure :3 at-15.

It. willthus; be understood that any desired range of; wave length of:llghtjmay be, used to illuminate, the copy: striplS. to give the-most de-' sirable photographicresult. Masks 49 between lamps 4| and prisms 47 permit only a selected strip of brilliant white light .toxstrike the prism from thesource 45. down. to its component color bandswhich may .be suitably directed therefrombyangular and rectilinear adjustment. Masks 59 permit only a selected band of the components of the light from the prism tostrike' the copy; Equalization of lighting by a particular color band is effected by adding illumination from low. illuminator 2l to that from high illuminator 20; .at illuminated strip [9 with the light of: the rangeof wave lengths striking the copy inreverse order 01' magnitude.

As an alternative construction for the above described illuminator housing,.and to avoidthe costv of optical glass prisms, a similar light-tight housing 46 fitted with a hinged coverrfi' may be provided as: shown in Figure 5, wherein a flashing, high intensity light source M islocated behind an elongated aperture 68 fitted withadjustable masks 69'2controlled by the adjusting screw 10. In this construction, I use a conventional'styleof optical filter i6,=selected for the process, which covers the elongatedaperture 68' and which is suitably clamped-to'theinside of the lamphousing. Light emitted from illuminatorZWiwhich has passed through filter 16 strikes the narrow copy band 19in the same mannersasthat described above:from illuminator 20,

and'similar devices are used to controlthe move-v ment of the illuminator with Irespectto the copy in order to cast a prescribed monochromaticslight over the entire copy area. A still furthermodification'may be resortedto by eliminatingzthe filter 76 of illuminator 20' and substituting tubular lamps constructed. with. a filtering .glasstcovering-of specialcharacteristics for the whitezlight flash tube In operation, the copyboard andcamera setup is made inthe usual manner, as is well. known in'the art, and the illuminator frame 10:15 rolled to a desired position with. respect .to the'copy. In using the flash lamp and prism illuminators for a source of monochromatic light, prescribed settings are made for the axial andxrectilinear location of theprism :and for the'maskopenings which direct light to and from the prism, depending upon thescolor band. desired. Forangular prism settings made outside. of housing .46 dials 1'! on the ends of the housings may. be. read in conjunction with indicators 18 fixed onthe extensionvshafts 55w Lamp switches are turned to on. positiontogivethe intermittent fiashlnz Prisms 4?" break the light.

9 of the specified color band and the apparatus is adjusted so that the band or strip 19 is disposed just below the copy. In accordance with customary camera procedure all extraneous light is avoided so that the only light striking the copy will be that from the illuminators 20 and 2! as they move upwardly. Switching means are then turned on which will cause the flashing illuminated strip I9 to slowly traverse the copy, and at the same time the camera shutter is opened so that the reflected light from the copy will be carried to the plate or film being exposed. After the illuminators have moved as a unit to an extreme'upward position past the copy, the lamp switching means will be turned off and the camera shutter closed.

This procedure will be repeated for each exposure made, the number of which, as has been explained will depend upon the particular process followed and upon the copy being reproduced, the illuminators being returned to the down position between exposures.

While the construction illustrated treats the use of my improvements with overhead camera, it'willbe apparent that the invention is not so limited and that suitable equipment may be accordingly devised for other types of reproduction cameras. Likewise, instead of vertical travel, the illuminators may be moved from side to side if necessary or desirable. Many other changes may be made in the details illustrated within the scope of the appended claims.

I claim:

1. In the art of producing a color separation negative of a color copy; focusing a copying camera on the color copy with the field of view of the objective lens of the camera including the entire surface of the copy, excluding extraneous light from the copy, then passing from a light source white light through a prism with said light source and said prism at least equal in length to one dimension of the copy, then masking the spectrum produced to form a band of light of a single predetermined color of substantially uniform density throughout and coextensive in length with one dimension of the copy but fractional in width compared to the other dimension thereof, projecting upon an extremity of the unlighted copy said band of light which uniformly illuminates only a zone of the copy corresponding to the area of the hand, then moving the band of light while always entirely within the field of view of the camera lens in the direction of its width and of the other dimension of the copy and with its origin at a constant distance from the copy until the moving band of light has scanned the entire copy and has uniformly illuminated successive zones thereof each corresponding to the hand area with said successive zones aggregating the entire surface of the copy, and simultaneously and continuously with. the scanning of the copy by the band of light exposing a photo sensitive element in the camera through the lens of the latter to the successively and uniformly illuminated zones of the copy which are each always entirely in the field of view of the lens whereby a single predetermined color separation negative of the copy is produced.

In the art of producing a color separation negative of a color copy as defined in claim 1 and wherein the copy is a color opaque copy with the objective lens of the camera including the entire surface of the copy on one side thereof and with the band of light scanning said one side of the copy.

, 3. In the art of producing a color separation negative of a color copy as defined in claim 1. andwherein the color copy is transparent copy while the lens of the camera includes the-entiresurface of one side of the copy and the band of. light scans the entire surface of the other side of the copy.

4. In the art of producing a color separation, negative of a color copy; focusing a copying. camerawith a color copy with the field-of view. of the objective lens of the camera including-the, entire surface of the copy, excluding extraneous. light from said copy; passing white light-from, two independent light sources through prisms with the light sources and prisms at least equal. in length to one dimension of the copy, to-produce elongated spectra; masking the spectra to produce light bands of the same single color andof; substantially uniform density throughout,.-;the nsimultaneously projecting upon an extremity-of the unlighted copy and in superimposed relation-. ship said bands of light and which are coextemt sive in length with one dimension-of the copy but fractional in width as compared to the other di- I mension-thereof, with said superimposed bands of light uniformly illuminating only a zone of the copy corresponding to the area of the superimposed bands, then moving the superimposed bands of light while always entirely within the field of view of the camera lens simultaneously while in superimposed relationship in the direction of their width and of the other dimension of the copy and with their origins always at the same and constant distance from the copy until the moving superimposed bands of light have scanned the entire copy and have uniformly illuminated successive zones thereof corresponding to the area of the superimposed bands, with said successive zones aggregating the entire surface of the copy, and simultaneously and continuously with the scanning of the copy by the superimposed bands of light exposing a photo sensitive element in the camera through the lens of the latter to successively and uniformly illuminated zones of the copy which are each always entirely in the field of view of the camera lens whereby a single predetermined color separation negative of the copy is produced.

5. In the art of producing a color separation negative of a color copy as defined in claim 4 and wherein the bands of light which are projected upon the copy are pulsated in timed relation to the rate of movement of the bands in scanning the copy, with the pulsations of the light of one band interlaced with the pulsations of the light of the other band to form substantially continuous illumination over the successive zones being scanned by the superimposed bands of lights.

6. In the art of producing color separation negatives of a multi-color copy; focusing a copying camera with the multi-color copy with the field of view of the objective lens of the camera including the entire surface of the copy, excluding extraneous light from the copy, producing a spectrum by passing white light from a light source through a prism with the source and prism at least equal in length to one dimension of the copy, successively masking the spectrum to produce successively bands of single color light and of substantially uniform density throughout with the light of each band different in color from the light of the other bands, successively projecting upon an extremity of the unlighted copy said single color bands of light with said bands 00- extensive in length with one dimension of the copy but fractional in width compared to the other dimension thereof and with said bands of light uniformly illuminating only a zone of the copy corresponding to the area of each band, moving each of the projected bands of light'while always entirely within the field of View of the camera lens in the direction of its width and of the 'other dimension of the copy and with its origin always at the same distance from the'copy until each moving band of light has scanned the entire copy and has uniformly illuminated successi-ve zones thereof corresponding to the band areas with said successive zones aggregating the entire surface of the copy, and simultaneously and continuously with the scanning of the copy by each band of light exposing a different photo sensitive element in the camera through the lens of the latter to the successively illuminated zones of thecopy which are always entirely in the field of view of the camera lens whereby a plurality of dlfl'erent color separation negatives are produced which can be used to reproduce the multi-color copy.

WILLIAM C. HUEBNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,001,549 Mertens Aug. 22, 1911 1,163,207 Brasseur Dec. 7, 1915 1,458,826 Janovjak June '12, 1923 1,792,046 Skaupy Feb. 10, 1931 1,927,693 Weisker ..1 Sept. 19, 1933 1,983,402 Rodman Dec. 4, 1934 2,011,544 Rodman Aug. 13, 1935 2,024,522 Harrison Dec. '17, 1935 2,052,625 Harrison Sept. 1, 1936 2,153,186 Henderson Apr. 4, 1939 2,206,521 Van Den Akker et al. July 2,1940 2,236,379 Pineo Mar. 25, 1941 2,464,761 Hail Mar. 15, 1949 FOREIGN PATENTS Number Country Date 181,633 Germany Mar. 2, 1907 166,028 Great Britain July 14, 1921 174,747 Great Britain Feb. 3, 1922 409,287 Great Britain Apr. 23, 1934 

1. IN THE ART OF PRODUCING A COLOR SEPARATION NEGATIVE OF A COLOR COPY; FOCUSING A COPYING CAMERA ON THE COLOR COPY WITH THE FIELD OF VIEW OF THE OBJECTIVE LENS OF THE CAMERA INCLUDING THE ENTIRE SURFACE OF THE COPY, EXCLUDING EXTRANEOUS LIGHT FROM THE COPY, THEN PASSING FROM A LIGHT SOURCE WHITE LIGHT THROUGH A PRISM WITH SAID LIGHT SOURCE AND SAID PRISM AT LEAST EQUAL IN LENGTH TO ONE DIMENSION OF THE COPY, THEN MASKING THE SPECTRUM PRODUCED TO FORM A BAND OF LIGHT OF A SINGLE PREDETERMINED COLOR OF SUBSTANTIALLY UNIFORM DENSITY THROUGHOUT AND COEXTENSIVE IN LENGTH WITH ONE DIMENSION OF THE COPY BUT FRACTIONAL IN WIDTH COMPARED TO THE OTHER DIMENSION THEREOF, PROJECTING UPON AN EXTREMITY OF THE UNLIGHTED COPY SAID BAND OF LIGHT WHICH UNIFORMLY ILLUMINATES ONLY A ZONE OF THE COPY CORRESPONDING TO THE AREA OF THE BAND, THEN MOVING THE BAND OF LIGHT WHILE ALWAYS ENTIRELY WITHIN THE FIELD OF VIEW OF THE CAMERA LENS IN THE DIRECTION OF ITS WIDTH AND OF THE DIMENSION OF THE COPY AND WITH ITS ORIGIN AT A CONSTANT DISTANCE FROM THE COPY UNTIL THE MOVING BAND OF LIGHT HAS SCANNED THE ENTIRE COPY AND HAS UNIFORMLY ILLUMINATED SUCCESSIVE ZONES THEREOF EACH CORRESPONDING TO THE BAND AREA WITH SAID SUCCESSIVE ZONES AGGREGATING THE ENTIRE SURFACE OF THE COPY, AND SIMULTANEOUSLY AND CONTINUOUSLY WITH THE SCANNING OF THE COPY BY THE BAND OF LIGHT EXPOSING A PHOTO SENSITIVE ELEMENT IN THE CAMERA THROUGH THE LENS OF THE LATTER TO THE SUCCESSIVELY AND UNIFORMLY ILLUMINATED ZONES OF THE COPY WHICH ARE EACH ALWAYS ENTIRELY IN THE FIELD OF VIEW OF THE LENS WHEREBY A SINGLE PREDETERMINED COLOR SEPARATION NEGATIVE OF THE COPY IS PRODUCED. 